Enthusiasts can grow their own crosnes, or Japanese artichokes (see picture). Otherwise they can be purchased from good greengrocer’s. If you cannot find any, replace with Jerusalem artichokes.
Blanch the artichokes in boiling water for 1 minute, then remove with a slotted spoon and place them on a tea towel with a little salt. Rub them gently with the tea towel to remove the delicate skins. Rinse under cold water and pat dry.
Heat the butter in a small frying pan until foaming, then add the artichokes and sauté until just golden. Add the sugar and cook until the artichokes are lightly caramelised. Add the tangerine juice and zest and simmer until reduced to a thick syrup. Season with salt and pepper, then add the tarragon and toss all together. Serve immediately.